Pathway but also for the effective cross-presentation of exogenous antigens in the context of MHC class I molecules [8]. In patients with cancer, the APM component expression is compromised, and its’ up-regulation is, therefore, desirable [10]. Remarkably, IRX-2 was found to be able to induce higher levels of APM expression than the 
conv. mix. It has been reported that cytokine mixtures containing INF-c are especially efficient in upregulating the APM component expression [9]. In contrast to the conv. mix, IRX-2 contains INF-c which could explain the higher levels of LMP2, TAP1, TAP2 and Tapasin expression in mDC. On the other hand, IFN-c alone is not a sufficient maturation signal for moDCs and only in combination with TLR or CD40 ligation enhances CCR7-driven DC migration and cytokine production [18]. Since IRX-2 up-regulated DC migration and IL-12p70 production, it is likely that a synergistic effect of INF-c and other cytokines included in IRX-2 was responsible for the observed effects. Recently, Lopez-Albeitero et al reported that cross-presentation of the MAGE3271-279 peptide correlated with TAP1 and TAP2 expression in APC in that higher expression of these APM components resulted in more effective presentation of the peptide to T cells [9]. In SRIF-14 chemical information addition, it has been shown, that a higher Human parathyroid hormone-(1-34) site density of MHC-class-I-peptide complexes on the surface of APC leads to more effective induction and expansion of the peptide-specific CTL [26]. We hypothesized, that DC matured in the presence of IRX-2 have a higher density of non-self-peptide-MHC Class I complexes on their surface and thus are more efficient in loading, transporting and presentation of these peptides. Indeed, using tumor-reactive CTL generated via IVS with PCI-13-loaded DC we showed that IRX-2 matured DC induced high-potency CTL. Although we found higher levels of the co-stimulatory molecules CD80 and CD86 on conventionally-matured DC, CTL generated in IVS cultures with IRX-2-matured DC turned out to be more effective in killing PCI-13 targets which served as an antigen source for cross-priming. It also appears that CTL generated in IVS with IRX-2-matured mDC, which have enhanced crosspriming capabilities, are more responsive to tumor-derived antigens in ELISPOT assays. These CTL gave the highest number of IFN-c spots upon co-incubation with IRX-2-matured DC presenting the antigen. We, therefore, suggest that the superior cross-priming capacity of IRX-2 matured DC is due to better cross-presentation of tumor cell-derived antigens likely resulting from up-regulated expression of APM components. In turn, this suggests that APM plays the central role in regulating the density of tumor-derived peptides present on the surface of mDC and that this step is of critical importance in the preparation ofDC-based 1527786 anti-cancer vaccines. However, effective cross-priming of T cells by APC is also critically dependant on cytokine-mediated signaling (i.e., signal 3) [27]. IL-12p70 appears to be essential for CTL priming by DC [19,28]. Okada et al. recently reported that clinical responses to DC-based vaccines correlated with IL-12p70 production by the DC used for therapy [29]. In contrast, IL-10, which is considered to be an inhibitory cytokine, has negative effects on priming of T-cell responses [30]. A higher ratio of IL12p70/IL-10 in supernatants of IRX-2-matured DC suggests that these DC are more likely to prime CTL responses. Since IRX-2 clearly increases the in vitro potency of moDC obtained.Pathway but also for the effective cross-presentation of exogenous antigens in the context of MHC class I molecules [8]. In patients with cancer, the APM component expression is compromised, and its’ up-regulation is, therefore, desirable [10]. Remarkably, IRX-2 was found to be able to induce higher levels of APM expression than the conv. mix. It has been reported that cytokine mixtures containing INF-c are especially efficient in upregulating the APM component expression [9]. In contrast to the conv. mix, IRX-2 contains INF-c which could explain the higher levels of LMP2, TAP1, TAP2 and Tapasin expression in mDC. On the other hand, IFN-c alone is not a sufficient maturation signal for moDCs and only in combination with TLR or CD40 ligation enhances CCR7-driven DC migration and cytokine production [18]. Since IRX-2 up-regulated DC migration and IL-12p70 production, it is likely that a synergistic effect of INF-c and other cytokines included in IRX-2 was responsible for the observed effects. Recently, Lopez-Albeitero et al reported that cross-presentation of the MAGE3271-279 peptide correlated with TAP1 and TAP2 expression in APC in that higher expression of these APM components resulted in more effective presentation of the peptide to T cells [9]. In addition, it has been shown, that a higher density of MHC-class-I-peptide complexes on the surface of APC leads to more effective induction and expansion of the peptide-specific CTL [26]. We hypothesized, that DC matured in the presence of IRX-2 have a higher density of non-self-peptide-MHC Class I complexes on their surface and thus are more efficient in loading, transporting and presentation of these peptides. Indeed, using tumor-reactive CTL generated via IVS with PCI-13-loaded DC we showed that IRX-2 matured DC induced high-potency CTL. Although we found higher levels of the co-stimulatory molecules CD80 and CD86 on conventionally-matured DC, CTL generated in IVS cultures with IRX-2-matured DC turned out to be more effective in killing PCI-13 targets which served as an antigen source for cross-priming. It also appears that CTL generated in IVS with IRX-2-matured mDC, which have enhanced crosspriming capabilities, are more responsive to tumor-derived antigens in ELISPOT assays. These CTL gave the highest number of IFN-c spots upon co-incubation with IRX-2-matured DC presenting the antigen. We, therefore, suggest that the superior cross-priming capacity of IRX-2 matured DC is due to better cross-presentation of tumor cell-derived antigens likely resulting from up-regulated expression of APM components. In turn, this suggests that APM plays the central role in regulating the density of tumor-derived peptides present on the surface of mDC and that this step is of critical importance in the preparation ofDC-based 1527786 anti-cancer vaccines. However, effective cross-priming of T cells by APC is also critically dependant on cytokine-mediated signaling (i.e., signal 3) [27]. IL-12p70 appears to be essential for CTL 
priming by DC [19,28]. Okada et al. recently reported that clinical responses to DC-based vaccines correlated with IL-12p70 production by the DC used for therapy [29]. In contrast, IL-10, which is considered to be an inhibitory cytokine, has negative effects on priming of T-cell responses [30]. A higher ratio of IL12p70/IL-10 in supernatants of IRX-2-matured DC suggests that these DC are more likely to prime CTL responses. Since IRX-2 clearly increases the in vitro potency of moDC obtained.